Granting and revoking authentication methods

Before Vertica can validate a user or client through an authentication method, you must first associate that authentication method with the user or role that requires it, with GRANT (Authentication).

Before Vertica can validate a user or client through an authentication method, you must first associate that authentication method with the user or role that requires it, with GRANT (authentication). When that user or role no longer needs to connect to Vertica using that method, you can disassociate that authentication from that user with REVOKE AUTHENTICATION.

Grant authentication methods

You can grant an authentication method to a specific user or role. You can also specify the default authentication method by granting an authentication method to PUBLIC, as in the following examples.

Associate v_ldap authentication with user jsmith:
```
=> GRANT AUTHENTICATION v_ldap TO jsmith;
```

Associate v_gss authentication to the role DBprogrammer:


=> CREATE ROLE DBprogrammer;
=> GRANT AUTHENTICATION v_gss TO DBprogrammer;

Associate client authentication method v_localpwd with role PUBLIC, which is assigned by default to all users:
```
=> GRANT AUTHENTICATION v_localpwd TO PUBLIC;
```

Revoke authentication methods

If you no longer want to authenticate a user or client with a given authentication method, use the REVOKE (authentication) statement as in the following examples.

Revoke v_ldap authentication from user jsmith:

=> REVOKE AUTHENTICATION v_ldap FROM jsmith;

Revoke v_gss authentication from the role DBprogrammer:
```
=> REVOKE AUTHENTICATION v_gss FROM DBprogrammer;
```
Revoke localpwd as the default client authentication method:
```
=> REVOKE AUTHENTICATION localpwd FROM PUBLIC;
```